In general, a waste heat recovery system applied to a vehicle commonly refers to a technique in which energy is recovered from exhaust gas discharged out of an engine. For example, such a technique may include a technique of generating power by immediately converting the flow of exhaust gas into rotational energy using a turbo generator, a technique of generating electric energy using a thermoelectric device, and a Rankine cycle technique of generating steam using heat of exhaust gas to rotate a turbine using the same.
The Rankine cycle technique among them has advantages of recovering energy from exhaust gas discarded as a working fluid and particularly utilizing engine coolant of a vehicle using water as a working fluid.